We define \(\mathbf {K}_{c, d}\)  as the \((c, d)\)  commutation matrix [1]}:
\(\mathbf {vec}(\mathbf {I}_d \otimes \mathbf {V}_i)= \left((\mathbf {I}_{d} \otimes \mathbf {K}_{c, d})(\mathbf {vec}(\mathbf {I}_d) \otimes \mathbf {I}_c) \otimes \mathbf {I}_{s}\right)\mathbf {vec}(\mathbf {V}_i)\) 
